A Model of Multiple Market:to Explain the Function of Merchant and Commerce by Cost of Transaction
多层市场模型：用交易费用解释商人和商业的作用

By setting up a model of multiple market on the basis of cost and efficiency of transaction,the present article explains the reason and function of merchant, and studies the equilibium of multiple market.It makes known that economic man minimizing the cost of tcansaction is the reason of causing the merchant and commerce,and merchant's function in cutting down the cost of transaction.It also makes an inquiry into the merchant's role in network economy.